Democrats are defending President Joe Biden after a report on his handling of classified documents raised concerns about his age and mental fitness.
Mr Biden will not be charged for keeping classified documents, but the report cast him as a "well-meaning, elderly man with a poor memory".
Vice-President Kamala Harris slammed the description as "gratuitous, inaccurate and inappropriate".
She also alleged the prosecutor was "clearly politically motivated".
Robert Hur, a Donald Trump appointee who has previously clerked for two well-known conservative judges, was appointed to lead the Biden classified document probe last year.
His selection by US Attorney General Merrick Garland that January came as the justice department faced criticism from Republicans over a separate special counsel appointment to investigate Donald Trump's alleged mishandling of top secret files.
But Mr Hur's publicly-released report included a letter from the White House asking that the comments about the president's memory be revised "in a manner that is within the bounds of your expertise and remit".
Ms Harris, who has previously served as a prosecutor, echoed that criticism at a news conference on Friday.
"The way that the president's demeanour in that report was characterised could not be more wrong on the facts, and clearly politically motivated," she said.
"When it comes to the role and responsibility of a prosecutor in a situation like that, we should expect there would be a higher level of integrity."
Democratic allies on Capitol Hill also told the OceanNewsUK they believed Mr Hur's remarks went beyond the scope of the investigation.
"I think it was an entirely inappropriate way to approach the remit of the special counsel and the role of the special counsel," Senator Jeff Merkley of Oregon said.
"It's unfortunate it wandered into territory that was so inappropriate."
Minnesota's Tina Smith called Mr Hur's comments "outrageous" and "despicable", accusing him of "blatantly politicising" his role as special counsel.
Since launching his re-election campaign, Mr Biden has been plagued by concerns about his age and mental capacities.
He is 81, just a few years older than the front-runner Republican candidate, former President Donald Trump, 77.
This report has done little to assuage voters' concerns. It alleged that Mr Biden could not remember when his son Beau died of cancer or when he served as vice-president during interviews with investigators.
But Democrats who spoke to the OceanNewsUK on Friday said they remain unconcerned about the president's mental faculties.
Summing up his takeaways from the report, Senator Jon Ossoff from Georgia said: "No charges recommended. Unusual commentary straying from what one would typically expect in a focused and substantive report. Ultimately just noise."
The youngest member of the Senate, Mr Ossoff emphasised that he had spent a "substantial amount of time" with the president in recent months.
"I've found him to be sharp, focused, impressive, formidable and effective," he said.
Mr Ossoff's colleagues agreed, including Senator Chris Van Hollen of Maryland, who called the president "thoughtful and experienced" at a Friday news conference.
Democrats remain "absolutely confident" in the president, he said. "We want to stick with somebody who understands what this country needs."
But some of his counterparts across the aisle said Mr Hur's observations had added fuel to the growing perception that Mr Biden is not up to the job of president.
"He's trying to do his best, and his best is beginning to concern me," North Carolina Senator Thom Tillis told the OceanNewsUK.
"I don't care if you're 78 or 178, if you're going to be the leader of the free world, you've got to be on your game 100%," the moderate Republican said.
Concerns about Mr Biden's age are "an enduring problem" for his re-election campaign, Larry Sabato, the director for the Center for Politics at the University of Virginia, told the OceanNewsUK.
Experts have noted that polling suggests Mr Trump does not face as much criticism from voters about his age, despite having similar gaffes as Mr Biden on the campaign trail.
In recent months, both Mr Biden and Mr Trump have made a series of public errors while publicly speaking, confusing names of world leaders and US politicians on several occasions.
But Mr Trump's bombastic style and "constant offensive posture" may fuel perceptions of him as a more energetic candidate, said Chris Borick, the director of the Muhlenberg College Institute of Public Opinion.
Worries about Mr Trump's age "don't seem to stick in the same way", he said.
But for Mr Biden, his campaign will have to be focused on addressing the perception that he is not mentally fit for office.
"The report adds to the steepness of [Biden's] efforts to overcome what is undoubtedly a significant hindrance to his campaign," Mr Borick said.
